Bluetooth: hci_bcm: Make suspend/resume functions platform_dev independent

Use dev_get_drvdata instead of platform_get_drvdata in the suspend /
resume functions. This is a preparation patch for adding (runtime)pm
support to the serdev path.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>